This invention relates generally to the field of telecommunications switching and more particularly to a distributed telecommunications switching system and method.
A variety of telecommunications networks have been used to establish communication between customer premises equipment (CPE) units and a central office. Most of these networks are formed in a xe2x80x9ctreexe2x80x9d structure, in which the central office is connected to several switching units, which are each connected to several smaller switching units, and so on along the xe2x80x9cbranchesxe2x80x9d of the tree. At the lowest level of switching units, each unit is connected to one or more CPE units.
To route addressed data or otherwise communicate with one of the CPE units, the central office determines which branch of the tree services the CPE unit in question. The data is then passed to the switching system for that branch, which in turn passes the data on to the next lower level in the switching hierarchy, and so on, until the data reaches the CPE unit.
This routing scheme requires that each switching system at each level in the hierarchy must store address and routing information for all of the CPE units serviced by it. If the customer base is expanded to include additional CPE units, then all switching systems routing traffic to the new CPE units must be reprogrammed to store the new address and routing information. Therefore, it is desirable to avoid establishing, maintaining, and updating address and routing information storage for the entire network at each switching system therein.
From the foregoing, it may be appreciated that a need has arisen for a telecommunications switching system that only maintains addressing and routing information for only the customer premises equipment that it services. Further, a need has arisen for a telecommunications network that avoids the tree structure approach of conventional telecommunications network. In accordance with the present invention, a distributed telecommunications system and method are provided which substantially eliminate or reduce disadvantages and problems associated with conventional telecommunications systems.
According to an embodiment of the present invention, there is provided a distributed telecommunications switching subsystem that includes a plurality of switching subsystems or channel banks. Each channel bank has a stored list of addresses. When a channel bank receives a data packet, it compares the address of the data packet to its stored list of addresses, and transmits the data packet to another channel bank if the address of the data packet does not correspond to any of the addresses in its stored list of addresses.
The present invention provides various technical advantages over conventional telecommunications systems. For example, one technical advantage is that each channel bank only stores a limited number of addresses pertaining to customers directly serviced by the channel bank and is effectively independent of the other channel banks in the system. Another technical advantage is that the modularity of the system allows expansion of service with minimal modification to the existing structure. A further technical advantage is that the channel banks may be located remotely from one another without significant degradation in service, allowing customers in different areas to be located xe2x80x9cclose to the switch,xe2x80x9d to decrease access times and improve service for the customers. Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
The present invention may be advantageously used to facilitate access to asynchronous transfer mode (xe2x80x9cATMxe2x80x9d) networks and environments.
The present invention provides for a technique and system that can be employed to interface with, and provide access to, an ATM network. The present invention may be employed to interface with an ATM network, such as central offices of a public switched telephone network or wide area networks that operate through the transmission of optical signals in ATM format, and to route information between the ATM network and designated subscriber interfaces. For example, the present invention may be interposed between a wide area network having an ATM backbone and customer premise equipment. Such placement allows for the present invention to provide different functions on behalf of the wide area network (such as a xe2x80x9cpolicingxe2x80x9d function, which regulates the traffic flow to wide area networks), as well as on behalf of the customer premise equipment (such as a rate adoption function for local area networks).
Multiple interconnected units (which can also be referred to as xe2x80x9cshelvesxe2x80x9d or xe2x80x9cchannel banksxe2x80x9d) are preferably used to implement the present invention. The multiple units may be physically located in a common place or in remote locations from one another. Each unit is associated with a plurality of subscriber interfaces, and performs distinct functions and procedures to the traffic deriving from the ATM network or subscriber interfaces. The cumulative effect of the multiple units is to form a technique and system that, among other things, routes and controls the ATM traffic amongst the various subscriber interfaces. As such, the present invention can be considered as a series of distributed ATM switches or nodes that collectively function as a single switching or multiplexing entity.
Preferably, the units are serially connected to one another (i.e., daisy-chained) such that any one unit is connected to one or two other units. The first and last units are connected to only one other unit, while the intermediate units between the first and last units are connected to two other units.